Process of making zinc formaldehyde hydrosulfite, (s.)



UNITED, .STATES PATENT NEW-YORK, N; 1Y-., ASSIGNOB To HERMAN A.

h. r m-1mm; on

OFFICE.

p I j tfi EltZ, on NEW YORK, Y. PROCESS OF' IVI-AfK IN'G ZINC'FORMALDEHYDE"HYDRGS'ULFITE, ls.)

Specification of Letters Patent,

Patented March 6, 1906.

To all whom, it may concern:

Be it known that I, EMILE A. FoURNEAUx, a citizen of the United States, residing at New York, in the county of New York and State of New York, have invented certain new and useful Improvements in Processes of Making Zinc Formaldehyde Hydrosulfite, of which the following is a specification.

In my copending application, Serial No. 252,867 ,filed March 30, 1905, I have described and claimed a novel basic zinc formaldehyde hydrosulfite occurring as a white crystalline preci itate having great reducing power and a big degree of stability and believed to correspond substantially to the formula:

ZnSO GH OH O.

In said application I have also described and claimed a method of producing this basic zinc salt, said method consisting in reacting with a suitable alkaline compound, as sodium carbonate, upon a solution of zinc hydrosulfite which has been treated with formaldehyde.

The above method is believed to proceed in accordance with the reaction:

I have discovered that this basic zinc salt,

may be obtained in a substantially quantitative manner and without the production of any expensive by-product, thus materially reducin the costof the salt. This is accomplished by reacting under definite conditions, as hereinafter'set forth, with zinc and av suitable acid upon an alkali formaldehyde bisulfite, which may be the by-product of the method described in my prior application above referred to or which may be otherwise prepared.

To avoid confusion of terms, the salts corresponding to the general formula M S.,O (M indicating any univalent metal,)heretofore considered as derived from the hypothetic .hvdrosulfurous acid of Bernthsen H 8 0 are herein termed hydrosulfites" in accordance with common usage, and the salts derived from the hypothetic hydrosulfurous acid of Schuetzenberger H SO are hereinafter referred to as hydrosulfites, (8.)

In preparing the basic zinc formaldehyde hydrosulfite (S) according to my present method I preferably treat a concentrated solution of an alkali formaldehyde bisulfite with equivalent proportions of zinc-dust and a suitable acid, as hydrochloric or sulfuric acid, under the following well-defined conditions: The reaction should take place at a temperature not less than centigrade, preferably between 80 to 90 centigrade.

The liquid should be stirred constantly to keep the insoluble matters in suspension, and theacid should be introduced below the surface of the liquid and so slowly that it is never present in the liquid in its free state to any substantial degree. Under these conditions the reaction takes place almost quantitatively as follows:

Example: To five hundred and fifty pounds sodium bisu lfite 55 Twaddell add the necessary amount of formaldeh 'de forty per cent, about one hundred and t irty-five pounds. Then heat gradually to 60 centigrade and add one hundred and twenty pounds zinc-dust pasted with the required amount of hot water. Then raise the temperature to or centigrade and allow the required amount of hydrochloric acid, 27 Twaddellsay two hundred poundsto run slowly into the above mixture, taking care to introduce the acid under the surface of the liquor. The acid must be added so slowly that it is readily taken up, and the reaction of the liquid on litmus must never be a yellowish red, at most wine color, and there must be no develo ment of hydrogen and no smell of thioforma dehyde, nor must formaldehyde be given off in any considerable quantities. During the entire reaction the liquid must be stirred energetically. is all introduced the stirring is continued until the reaction of the .iquid becomes neutral.

The liquid is then allowed to stand uiitil the zinc salt is entirely separated, so that the mother-liquors no longer or but very slightly reduce a solution of indi o sulfonic acid.

I claim-- 1 an alkali formaldehyde bisulfite with zinc 1 and supplyin a suitable acid at such rate In the above example the hydrochloric that the re ence of free acid is substanacid can be replaced by sulfuric acidsay i tially avoided, thereby roducing basic zinc four hiindred and twenty pounds-at 25 formaldehyde hydrosul te (S), substantially Twaddell. 1 as described.

The resulting white crystalline precipitate In testimony whereof I afiix my signature of basic zinc formaldehyde hydrosolfite (S) is in presence of two Witnesses. then separated from the mother-liquors by EMILE A. FOURNEAUX. filtration and washed with cold water to re- Witnesses: move the sodium chlorid or sulfate formed PAUL LOESERY, during the reaction. ALEXANDER Sc wAnsMAN.

The process which consists in reacting on 

